Emergency tripping systems have long been utilized to shut off industrial turbines in the event certain operating conditions occur. Such tripping systems are commonly designed around certain pressure readings. Those pressure readings, and the maintenance of such pressures within a prescribed range, include a pressure or vacuum reading in the condenser vacuum which is indicative of exhaust pressure, maintenance of oil bearing pressure, the prevention of an increase in the thrust bearing oil pressure and a monitoring of the autostop oil pressure. Often, the autostop oil pressure line may be in communication with a solenoid valve.
Of course, other components may form part of an emergency tripping system such as anticipator trip valves which may be tripped or activated by excessive speed of the turbine. A turbine emergency trip valve may be incorporated along with stop valve bypass trips, auxiliary pilot valve trips, lock out sleeve trips and other emergency trip functions, depending upon the manufacturer. Those skilled in the art and familiar with the turbine designs of Westinghouse and General Electric will be familiar with various trip functions associated with these turbines.
One problem associated with emergency tripping systems for industrial turbines, engines and other similar apparatuses is the cumbersome design of such systems. Specifically, piping must be provided for each pressure sensing function which is then connected to a separate transmitter. Often, it is desirable to use redundant transmitters to monitor each trip function. Specifically, transmitters are prone to failure and require frequent maintenance. Manufacturers therefore often utilize two or three transmitters to monitor one trip function with the criteria that at least two of the transmitters must register an alarm status before a shut down procedure is begun.
With the common use of multiple redundant transmitters or multiple redundant distributed control system (DCS) inputs for each trip function, the piping, wiring and mounting for the various trip functions becomes cumbersome to install and difficult to maintain. Specifically, typical systems include multiple manifolds with custom mounts that are interconnected with extensive quantities of tubing and pipe. Still further, due to the cumbersome design of these systems, there is no easy way to gain access to the transmitters or valves for service and maintenance. Thus, an improved emergency tripping system for turbines and other industrial apparatuses is needed that is less cumbersome, reliable and easy to install and maintain.